Added
- Use System Theme — a new toggle on the Schedule tab that follows your OS light/dark setting (macOS, Windows, Linux). The dark theme turns on when your system is dark and off when it's light, reacting live as the OS switches — no page reload needed.

Behavior
- "Use System Theme" and "Enable Schedule" are mutually exclusive: turning one on switches the other off. Your saved schedule times are preserved, so re-enabling the schedule won't ask you to re-enter them. Both are off by default.

Notes
- Works through the browser's prefers-color-scheme, so there's no native helper to install. In Firefox this follows the active browser theme — keep the theme set to "Automatic" (System) for it to track the OS.

Added
- Built-in HSV color picker right inside the popup (saturation/value square + hue slider) — no more native dialog that closed the popup. Dependency-free.

Improved
- Dark theme now covers site top bars (header, nav, [role=banner|navigation]) and more structural containers, so headers stop staying white on many sites.
- Lighter background messaging: theme reloads are broadcast once, in parallel, only to http/https tabs.

Fixed
- Hex color input now works in the popup (previously only on the settings page).
- Schedule time fields accept direct typing — focus a field and type, no need to clear first.
- The popup footer shows the real extension version (was hard-coded to v1.0.0).

Changed
- Removed the separate options page — the popup is now the single, fully capable UI.
- Colors are validated before injection (defense in depth); CSS injects safely even before <head> exists.

Internal
- Added a zero-dependency test suite (npm test) covering color math, CSS generation, scheduling and a resource/bundle-size budget.